Effects of selective inhibition of nNOS and iNOS on neuropathic pain in rats.
Mol Cell Neurosci
; 105: 103497, 2020 06.
Article
em En
| MEDLINE
| ID: mdl-32353527
ABSTRACT
Various animal models have been employed to understand the pathogenic mechanism of neuropathic pain. Nitric oxide (NO) is an important molecule in nociceptive transmission and is involved in neuropathic pain. However, its mechanistic actions remain unclear. The aim of this study was to better understand the involvement of neuronal and inducible isoforms of nitric oxide synthase (nNOS and iNOS) in neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve in rats. We evaluated pain sensitivity (mechanical withdrawal thresholds using Randall and Selitto, and von Frey tests, and thermal withdrawal thresholds using Hargreaves test) prior to CCI surgery, 14 days post CCI and after intrathecal injections of selective nNOS or iNOS inhibitors. We also evaluated the distribution of NOS isozymes in the spinal cord and dorsal root ganglia (DRG) by immunohistochemistry, synthesis of iNOS and nNOS by Western blot, and NO production using fluorescent probe DAF-2 DA (DA). Our results showed higher number of nNOS and iNOS-positive neurons in the spinal cord and DRG of CCI compared to sham rats, and their reduction in CCI rats after treatment with selective inhibitors compared to non-treated groups. Western blot results also indicated reduced expression of nNOS and iNOS after treatment with selective inhibitors. Furthermore, both inhibitors reduced CCI-evoked mechanical and thermal withdrawal thresholds but only nNOS inhibitor was able to efficiently lower mechanical withdrawal thresholds using von Frey test. In addition, we observed higher NO production in the spinal cord and DRG of injured rats compared to control group. Our study innovatively shows that nNOS may strongly modulate nociceptive transmission in rats with neuropathic pain, while iNOS may partially participate in the development of nociceptive responses. Thus, drugs targeting nNOS for neuropathic pain may represent a potential therapeutic strategy.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Nervo Isquiático
/
Gânglios Espinais
/
Neuralgia
/
Óxido Nítrico
Limite:
Animals
Idioma:
En
Revista:
Mol Cell Neurosci
Assunto da revista:
BIOLOGIA MOLECULAR
/
NEUROLOGIA
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Brasil